Curculin exhibits sweet-tasting and taste-modifying activities through its distinct molecular surfaces
Curculin exhibits sweet-tasting and taste-modifying activities through its distinct molecular surfaces
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DOI：
10.1074/jbc.c700174200
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发表时间：
2007-11-16
影响因子：
4.8
通讯作者：
Kato, Koichi
中科院分区：
文献类型：
--
作者：
Kurimoto, Eiji;Suzuki, Maiko;Kato, Koichi
仙茅素是从马来西亚的一种植物仙茅中分离出来的，具有一种有趣的性质，可以将酸味转变为甜味。除了这种味觉调节活性，仙茅素本身也能产生甜味。虽然这些活动已归因于仙茅素的异二聚体异构体，而不是同源二聚体，这种蛋白质的双重作用的潜在机制在很大程度上是未知的。为了确定这些活动的关键网站，我们进行了突变和重组仙茅蛋白的结构研究。在比较仙茅素同源二聚体和异源二聚体晶体结构的基础上，设计了一系列突变体，并进行了品尝试验。根据其突变效应的三维结构上的氨基酸残基的映射显示仙茅素异二聚体通过其部分重叠但不同的分子表面表现出甜味和味道修饰活性。这些发现表明仙茅素异二聚体的两种活性通过其与T1 R2-T1 R3异二聚体甜味受体的两种不同的相互作用模式表达。
Curculin isolated from Curculigo latifolia, a plant grown in Malaysia, has an intriguing property of modifying sour taste into sweet taste. In addition to this taste-modifying activity, curculin itself elicits a sweet taste. Although these activities have been attributed to the heterodimeric isoform and not homodimers of curculin, the underlying mechanisms for the dual action of this protein have been largely unknown. To identify critical sites for these activities, we performed a mutational and structural study of recombinant curculin. Based on the comparison of crystal structures of curculin homo- and heterodimers, a series of mutants was designed and subjected to tasting assays. Mapping of amino acid residues on the three-dimensional structure according to their mutational effects revealed that the curculin heterodimer exhibits sweet-tasting and taste-modifying activities through its partially overlapping but distinct molecular surfaces. These findings suggest that the two activities of the curculin heterodimer are expressed through its two different modes of interactions with the T1R2-T1R3 heterodimeric sweet taste receptor.